Data backup and data security are of great importance in our digital society. Without data backup, important user data such as documents, spreadsheets, photos, and videos on the storage device could disappear. Without data security, a user's sensitive data could fall into wrong hands, resulting in identity theft and other serious consequences. In short, sensitive information needs to be backed up, and in a secure fashion. One way to secure the access to a data backup is to encrypt it.
Block based backup solutions are popular these days. Formats for block based backup solutions are mountable. Examples for such mountable formats include Virtual Hard Disk (VHD), Hyper-V Virtual Hard Disk (VHDx), and Virtual Machine Disk (VMDK), etc. If an unauthorized user can gain access to one of these files on the backup media, s/he would be able to perform native mount operations to steal the backed up data. With just a mount operation, the user's backed up data, in its entirety, will be visible to the hacker or intruder. So encryption is very much desired for these mountable backup format solutions.
Conventional backup technologies secure the access to a block based backup file by encrypting the entire backup image. This is time consuming and therefore lengthens the backup time.